I havent touched the calcium in my 40 for a year lol. I really havent paid any attention to it since all i've got are softies which dont use calcium as far as i'm aware. I do have a few lps and sps and they're doing fine, so i'm convinced that my calcium is at least halfways decent haha..
As for the t5's, those are t5 HO right? Or just normal output ones? If they're High Output, then you can grow quite a lot of stuff...but not if they're NO or Normal output.